Using Thunderbird 115.11.1 (32-bit) on Windows, I have it set to remove msgs from the server at an interval
and don’t wish to change that.

When travelling I use my phone to collect msgs. Often I forget to shut T/Bird down as I
leave and so while away I see no emails until I return as the PC gobbles them all.

So I’m seeking a filter/script that would run on receipt of all msgs looking for a
specially crafted email so I can send myself an email to tell T/Bird to close.

I’ve looked at filters but they don’t seem to have a way of doing this, and other add-ons/etc are functional overkill for this simple task.

Conceptually I’d like something simple like:
If the email msgfrom matches myaddy and msgsubject matches secretcode then close.